1. Evaluation of an Intervention to Improve Immunization Up-to-Date Rates Among Children Attending WIC in South Los Angeles
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2. Contributing Authors:
Presenting Author:
Jennifer Chiprich, PhD
Contributing Authors:
Julia Heinzerling, MPH
Lizz Romo, BS, RD
Terry Silberman, DrPH
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3. Background South LA Health Projects conducted
IZ promotion activities at 10 South LA
WIC Sites
April 2006 – December 2007
AIR (assessment, information and referral)
MVP (voucher incentive)
Assessment, information and referral (AIR) activities include assessing children’s immunization needs, providing parents with immunization information, and referring
children to their doctor to get needed immunizations (if they don’t have a medical home, we provided a referral list).
MVP: Monthly Voucher Pick-up (MVP) is the strategy of issuing only 1 month of WIC vouchers, instead of the customary 2-3 months worth at a time, to participants whose children are past due for immunizations; participants return to WIC monthly until their children are current.
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4. Background Additional intervention for parents of
under-immunized children
Follow-up phone calls (up to 3 attempts)
Follow-up letter
Tracking tool
ITSLA
(Immunization Tracking System Los Angeles)
The intervention was done by administration staff
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5. Study Population and Groups
Children served at one of the 10 South LA WIC sites between April – December 2006 and 3 or 5 months of age and under-immunized when screened
Intervention Group
Children who were under-immunized and served at a WIC site on an even day of the month. (n = 600)
Control group
Children who were under-immunized and served at a WIC site on an odd day of the month. (n = 508)
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6. Demographics Race/Ethnicity Intervention Control Asian 0.3 % 0.2 %
African-American
15.4
7.9
Hispanic
73.9
78.6
Pacific Islander
0.3
0.2
Native American
Multiracial
5.8
8.1
Refused
1.5
2.0
White
1.3
1.0
No answer
1.8
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7. Intervention Control group Intervention group
Received MVP and AIR at WIC
Intervention group
Received MVP and AIR + phone call and letter
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8. Results IZ
Received Intervention
Did Not Receive Intervention
DTP(3)
337 (70.2%)
449 (71.7%)
Polio (2)
443 (92.3%)
578 (92.3%)
Hib (2)
438 (91.3%)
576 (92.0%)
HepB (2)
466 (97.1%)
598 (95.5%)
Up-to-Date
334 (69.6%)
447 (71.4%)
There is no significant difference in proportion between the groups at 13 months.
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9. Results Received Intervention vs. Did Not Receive
7th month IZ
Chi-square
P-value
DTP (3)
0.2174
0.6410
Polio (2)
0.0299
0.8628
Hib (2)
0.3122
0.5763
HepB (2)
1.4330
0.2313
Up-to-date
0.2375
0.6260
13th month IZ
Chi-square
P-value
DTP (3)
0.3040
0.5814
Polio (2)
0.0006
0.9800
Hib (2)
0.2073
0.6489
HepB (2)
1.8009
0.1796
Up-to-date
0.4348
0.5096
When examined by ‘current’ status, in an effort to decrease the attrition in the sample, the p-values remain non-significant. Current status was defined as those who had attended one of the SLAHP WIC offices in their 10-12th month and had brought their immunization cards. It was chosen to do the analysis using the receiving intervention group to show the ‘real life’ presentation of the study.

10. Results Change in UTD Status between 7th and 13th month
Group
Chi-square
P-value
Received vs. did not receive intervention
1.3216
0.2514
Approximately the same percentage of participants in each group changed UTD status between their 7th and 13th month:
Received intervention (24.4%)
Did not receive intervention (21.5%)
This table shows the chi-square result comparing change in UTD status between the 7th and 13th month for the two groups.
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11. Results Two analyses based on contact mode
Receiving a letter only compared to receiving both a letter and phone contact.
Receiving phone contact only compared to receiving both a letter and phone contact.
There were no significant differences
The significance of these results are obviously influenced by the lack of significance in the primary hypothesis. P-values for the analysis were not close to borderline significance. There were 450 in the study that received contact: 210 (46.7%) that received phone contact and 240 (53.3%) that received a letter by no phone contact.
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12. Discussion
No statistically significant difference based on chi-square analysis between the received intervention group and control group (at 13 months).
Interpretation: There is no significant increase in UTD rates at the 13th month with the use of follow-up calls and letters, AIR and MVP over the UTD rates with use of AIR and MVP alone.
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13. Discussion Bias Randomization of the subjects Blinding Other factors
Media coverage of immunizations
Variables not measured by the SLAHP team
External validity
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14. Comparison with the literature
Similar to findings of Hoekstra et al, in Journal of Pediatrics, (1)
Other findings consistent with other published work
DTaP most missed vaccine by children (2)
High baseline rates and effectiveness of MVP in similar populations (3)
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15. Conclusion
Based on the findings of this study, we discontinued the supplemental telephone and mail follow-up.
We continue to administer AIR and MVP at all 10 SLAHP WIC sites.

16. Evaluation Specialist South Los Angeles Health Projects
To Learn More…
Jennifer Chiprich, PhD
Evaluation Specialist
South Los Angeles Health Projects
(323) Ext. 287
Acknowledgements
Immunize LA Kids was supported by the Centers for Disease Control and Prevention (CDC) under the REACH 2010 Initiative and the California Department of Health Services Immunization Branch.
Immunize LA Kids received institutional support from the Los Angeles Biomedical Research Institute at
Harbor-UCLA Medical Center.
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17. References
1. Hoekstra EJ, LeBaron CW, Johnson-Partlow T, Does reminder-recall augment the impact of voucher incentives on immunization rates among inner-city infants enrolled in WIC?, J Pediatr Aug; 135(2 Pt 1):
2. Ghosh TS, Patnaik JL, Bennet A, Trefren L, Vogt RL; Assessment of missing immunizations and immunization-related barriers among WIC populations at the local level. Public Health Rep Sep-Oct; 122(5):602-6.
3. Ashkar SH, Dales LG, Averhoff, F, Shefer A, Higa J, et al. The effectiveness of assessment and referral on immunization coverage in the special supplmenetal nutrition program for women, infants and children. Arch Pediatr Adolesc. Med May; 157(5):
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